services/mail: reduce logspam

reduce logspam by out mail services by seeting them to logleven 5
(notice) and 3 (error)

services/mail.nix

@@ -5,6 +5,11 @@
       sources.nixos-mailserver.outPath
   ];
 
+  # reduce log spam
+  systemd.services.rspamd.serviceConfig.LogLevelMax = 3; # this is set to error because rspamd regularly complains about not enough learns
+  systemd.services.postfix.serviceConfig.LogLevelMax = 5; # = notice
+  systemd.services.dovecot2.serviceConfig.LogLevelMax = 5; # = notice
+
   mailserver = {
     mailDirectory = "/persist/mail";
     enable = true;